Feb 25 (Reuters) - Britain's Thames Water has asked KKR

and Castle Water to provide more detail on their equity

bids for the water utility, Bloomberg News reported on Tuesday,

citing people familiar with the matter.

The country's biggest water supplier, which has 18 billion

pounds of debt, has received non-binding offers from U.S.

Investment firm KKR and UK-based water firm Castle for 4 billion

pounds each, Bloomberg had earlier reported.

An offer from London-based asset manager Covalis Capital,

who is also a junior creditor of Thames, is currently less

favoured by Thames Water, the report said.

Covalis, in partnership with French waste management firm

Suez Group, has offered a 1 billion pounds investment in Thames.

The plan involves selling certain assets before floating the

remainder of the group, while giving Britain a golden share.

Thames, KKR, Covalis and Castle did not immediately respond

to Reuters requests for comment.